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Pediatric Supination – Inversion Ankle Fracture:


- Discussion:
    - most common type of pediatric ankle fracture;
    - involves adduction injury to a supinated foot;

- Classification:
  - type I: (involves fibula);
         - separation of distal fibular epiphysis (SH I or II frx);
         - epiphyseal separation involves distal fibula & is due to inversion force;
         - may be confused w/ ankle sprain;
         - palpation of fibular physis will elicit tenderness;
         - key to dx is soft tissue swelling on x-rays, located over distal fibular epiphysis;
                - look for slight medial displacement;
                - look for widening of the physis on oblique views;
                - comparison views of the opposite ankle is helpful;
         - treatment: short leg cast for 3-4 weeks;
         - complications:
                - shortening of fibula, with lateral shifting of talus;
                - resulting laterally increased pressure on tibia causes some growth inhibition & resulting valgus deformity of ankle;
  - type II Frx: (additional injury to distal tibia);


- Complications: Varus Deformity:
    - due to asymmetric arrest of distal medial tibial growth plate:
    - most common angular deformity seen in this injury;
    - osseous bridge in medial part of physeal plate may develop after a Salter Harris III or IV injury;
    - if the growth plate is damaged at the time of injury, even an undisplaced frx can develop a varus deformity;
    - radiographs:
           - Harris growth arrest lines are seen to converge over the physis at the point of injury;
           - damaged physis may appear radiodense;
           - tomograms help define the bone bridge;
    - prevention:
           - anatomical reduction of the fracture may reduce the incidence of varus growth deformity;
           - in late cases, consider physeal bar resection or opening wedge supra-malleolar osteotomy;

- Case Example:
      - 12-year-old male who sustain a left supination inversion frx, which was treated w/ percutaneous pinning; 

       

      - key points:
            - the medial pin was incorrectly placed across the physis as opposed to parallel to it;
            - a non anatomic reduction was accepted, which may have led to growth plate arrest;
            - this patient would have been better served w/ an open reduction; 

           
                  right ankle         left ankle



Supination-adduction injuries of the ankle in children--radiographical classification and treatment.

Roentgen stereophotogrammetric analysis of growth pattern after supination-adduction ankle injuries in children.